i DIY-ed this a few years back.
I followed the instructions on this site How to Remove Window Tint: 20 steps (with pictures) - wikiHow (not sure if this is the exact site but same prodecure).

Only 2 of the defogger lines were broken.

I remember a product from soft99 ("circuit repairer" ata yung name) that you might be able use to repair the broken lines.
I wasn't able to try it personally.

Hope this helps.